<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title></title>
	</head>
	<body>
		<button type="button" id="btn">button</button>
		<script type="text/javascript">
			const button = document.getElementById('btn');
			console.log(this)
			button.addEventListener('click',function(){
			
			(()=> {
			    console.log(this === window) // false
			    this.innerHTML = 'clicked button'
			})()
			} )
		</script>
	</body>
</html>
